Acidic Aqueous Ethanol Research Articles

Facile Synthesis of Pyrazolopyranopyrimidines by Synergism of Ultrasound Irradiation and Biocompatible Inulin Biopolymer as Catalyst

AbstractInulin, a natural polysaccharide has been utilized as a novel biodegradable, efficient, and environmentally benign catalyst for the ultrasound‐assisted one‐pot, single‐step multicomponent formation of a library of pyrazolopyrano[2,3‐d]pyrimidine‐diones 5(a‐k) from the reaction of ethyl acetoacetate, hydrazine hydrate, aromatic aldehydes, and barbituric/ thiobarbituric acid in aqueous ethanol (1 : 1) at 50 °C. This facile methodology offers a metal‐free, sustainable, selective synthesis of pyrazolopyrano[2,3‐d]pyrimidine‐diones with no by‐product having excellent product yield (≥90 %) in a shorter reaction time. Additionally, the biocompatible inulin is recyclable for up to five consecutive runs without much decrease in its catalytic potential. Inulin has been characterized by spectral techniques such as XRD, FTIR, Raman, and SEM. It shows remarkable stability in the reaction medium as evident from the zeta potential value of −21.39 mV and hydrodynamic diameter of 459.5 nm. Novel pyrazolopyrano[2,3‐d]pyrimidine‐diones (5g, 5h, 5j, and 5k) were also synthesized using this protocol and the synthesized compounds were examined for their antimicrobial activity.

Removal of pararosaniline hydrochloride (basic red 9) from aqueous system with lignocellulose fraction of sugarcane bagasse as adsorbent

The removal of pararosaniline hydrochloride (BR9) from an aqueous system using lignin and holocellulose in extractive-free SCB (eSCB) as a natural and low-cost adsorbent was evaluated. Adsorption experiments were carried out at various initial pH (4−8) and initial dye concentrations (10 mg/L to 500 mg/L) and at different temperatures (303–333 K), to assess its uptake rate and equilibrium uptake. The uptake kinetics were fitted with various models, where the Elovich model and a newly proposed multi-mechanistic model were found to best describe the uptake rate and process. Adsorption of BR9 onto eSCB, involved the simultaneous adsorption at different locations of the eSCB matrix. The adsorption capacity of eSCB for BR9 was found to be 48.98 mg/g at 303 K. From thermodynamic analysis, it was inferred that the adsorption process was exothermic (ΔH = −4.04 kJ/mol), and spontaneous (ΔG = −35.40 to −27.5 kJ/mol). Apart from adsorption, the desorption and subsequent reuse of eSCB for BR9 adsorption were also explored and reported for the first time. The use of acidic aqueous ethanol with HCl as the acid helps the removal of BR9 from eSCB. As an adsorbent for BR9, eSCB could be reused at least 4 times.

Calorimetric study of the thermodynamics of iron (III) complexation with nicotinic acid in aqueous ethanol

Calorimetric study of the thermodynamics of iron (III) complexation with nicotinic acid in aqueous ethanol

Efficient and Greener Synthesis of Functionalized Isoniazid Azomethines from Aromatic Aldehydes and Isatins Using Citric Acid in Aqueous Ethanol

Citric acid was discovered as an efficient catalyst for the rapid synthesis of pharmacologically important isoniazid azomethines by condensation of aromatic aldehydes and isatins with isoniazid in aqueous ethanol under reflux condition. The advantages of the described method include the use of readily available starting materials, biodegradable greener catalyst, and mild reaction conditions. The products were obtained in high yield within short reaction time and no need for column chromatography purification.

Newly Designed Mesoporous Silica and Organosilica Nanostructures Based on Pentablock Copolymer Templates in Weakly Acidic Media.

We developed a new category of porous silica and organosilicas nanostructures in a facile method based on weakly acidic aqueous-ethanol media by utilizing two different pentablock copolymer templates of type PLGA-PEO-PPO-PEO-PLGA. Pluronic block templates were used mainly to prepare these pentablock copolymers with different molecular weights and volume ratios. Silica precursor tetraethyl orthosilicate and organosilicas precursor 1,4-bis(triethoxysilyl)benzene have been used as main source for synthesizing the silica and organosilicas samples. Weak Lewis acids iron(III) chloride hexahydrate, aluminum(III) chloride hexahydrate, and boric acid were utilized as catalyst instead of any strong inorganic acids and the molar ratio of catalyst/precursor has been optimized to 1–2 for preparation of ordered mesostructures. Reaction temperatures have been optimized to 25 °C for pure silica and both 25 °C as well as 40 °C for organosilicas to get the best result for mesostructures. A detailed analysis by using various analytical techniques like synchrotron small angle X-ray scattering, nitrogen sorption, transmission electron microscopy, scanning electron microscope, solid-state 29Si CP-MAS nuclear magnetic resonance (NMR), and so on has revealed well developed mesostructures with surface area of 388–836 m2/g for silica and 210–691 m2/g for organosilica samples, respectively. Furthermore, bimodal typepores have been observed from pore size distribution plot of the samples. Thermal stability of the materials was up to 400 °C as analyzed by thermogravimetric analysis.

Hetero-epitaxial growth of chabazite zeolite membranes using an RHO-type seed layer

High-quality chabazite (CHA) zeolite membranes were synthesized from organotemplate-free aluminosilicate gel via epitaxial growth using RHO-type seed layer. Both zeolite RHO seeds (Si/Al = 2.4) and the synthetic gel containing cesium species led to the formation of the CHA zeolite with a high Si/Al ratio of 3.0 and a short synthesis time of 12 h. The effects of seed particles and crystallization time on membrane formation, pervaporation performance, and acid resistance were also investigated. The obtained CHA@RHO membrane prepared using commercial tubular mullite support showed a high flux of 2.3 kg m−2 h−1 and a good separation factor of 3500 for 10/90 wt% water/ethanol mixture at 348 K, which are comparable to those of homogeneous CHA membranes crystallized in organotemplate-free systems from previous reports. Moreover, these membranes were stable for the dehydration of acidic aqueous ethanol solution (with a pH value of 3.0) at 348 K for 8 d.

Mandelic Acid: An Efficient Organo-catalyst for the Synthesis of 3-substituted-3- Hydroxy-indolin-2-ones and Related Derivatives in Aqueous Ethanol at Room Temperature

Background: Indoles and various indolyl derivatives are very common in naturally occurring biologically active compounds. Many methods are being developed for the synthesis of various bioactive indole derivatives. Objective: Synthesis of biologically promising structurally diverse indole derivatives under mild and environmentally benign conditions. Methods: Synthesis of 3-hydroxy-3-(5-(trifluoromethoxy)-1H-indol-3-yl)indolin-2-one was achieved by the reaction of an equimolar mixture of isatin and 3-(trifluoromethoxy)-1H-indol using 20 mol% of mandelic acid as catalyst in aqueous ethanol at room temperature. Under the same optimized reaction conditions, synthesis of 3-(3-hydroxy-2-oxoindolin-3-yl)chroman-2,4-diones was accomplished via the reactions of substituted isatins and 4-hydroxycoumarin. On the other hand, 2-hydroxy-2-(indol-3-yl)- indene-1,3-diones and 10-hydroxy-10-(5-methoxy-1H-indol-3- yl)phenanthren-9(10H)-one were synthesized from the reactions of indoles and ninhydrin or 9,10-phenanthrenequinone respectively using the same 20 mol% of mandelic acid as an efficient organo-catalyst in aqueous ethanol at room temperature. Results: Mild, safe and clean reaction profiles, energy efficiency, high atom-economy, use of naturally occurring non-toxic organo-catalyst, easy isolation procedure by avoiding column chromatographic purification and gram scale production are some the major advantages of this developed protocol. Conclusion: A simple, straightforward and eco-friendly protocol has been developed for the efficient synthesis of biologically promising novel 3-hydroxy-3-(5-(trifluoromethoxy)-1H-indol- 3-yl)indolin-2- one, 3-(3-hydroxy-2-oxoindolin-3-yl)chroman-2,4-diones, 2-hydroxy-2-(indol-3- yl)-indene-1,3-diones and 10-hydroxy-10-(5-methoxy-1H-indol-3-yl)phenanthren-9(10H)-one using a catalytic amount of mandelic acid in aqueous ethanol at room temperature.

Facile synthesis of NC(sp3)O pincer palladium complexes and their use as efficient catalysts for Suzuki-Miyaura reaction of aryl bromides in aqueous medium

Two NC(sp3)O pincer palladium(II) complexes 3a-3b were readily prepared in high yields in only two steps. Of the first step, catalytic hydrophosphination of 2-alkenoylpyridines and subsequent in situ phosphine oxidation produced the NC(sp3)O pincer preligands 2a-2b. The second step is palladation of the preligands 2a-2b where PdCl2 was used as the Pd source to afford the desired Pd pincers 3a-3b via C(sp3)-H bond activation. Single crystal X-ray diffraction analysis of complex 3a unambiguously confirmed the NCO tridentate coordination mode of the complexes. The two complexes 3a-3b were applied to catalyze the Suzuki-Miyaura reaction. Complex 3b was found to be more efficient and exhibited very high activity in the Suzuki reaction of structurally diverse aryl bromides with arylboronic acids in aqueous ethanol under air. At a reaction temperature of 70 °C, a TON of up to 1.9 × 105 and a TOF of up to 9800 h−1 were achieved. At lower temperatures 3b was still very active, giving a TON of up to 9.5 × 103 and a TOF of up to 3900 h−1 at room temperature.

Ultrasound-assisted and trisodium citrate dihydrate-catalyzed green protocol for efficient and one-pot synthesis of substituted chromeno[3′,4′:5,6]pyrano[2,3-d]pyrimidines at ambient conditions

A simple, straightforward, and highly efficient multicomponent one-pot synthesis of a series of pharmaceutically interesting functionalized chromeno[3′,4′:5,6]pyrano[2,3-d]pyrimidines has been developed based on a low-cost and environmentally benign trisodium citrate dihydrate catalyst via ultrasound-assisted tandem reactions of 4-hydroxycoumarin, aromatic aldehydes, and barbituric acid/thiobarbituric acid in aqueous ethanol at ambient conditions. Metal-free synthesis, high atom-economy, good to excellent yields, short reaction time, operational simplicity, eco-friendliness, and mild reaction conditions are some of the important features of his protocol.

Effect of Solvation on the Acid–Base Equilibria of Succinic Acid in Н2О–EtOH and Н2О–DMSO Solutions

The Gibbs energies of transferring succinic acid from water to aqueous ethanol and aqueous dimethylsulfoxide solvents are determined according to solubility. An increase in the negative values of the Gibbs energy upon moving from water to aqueous–organic solvents is observed. The effect the composition of solvents has on the acid–base properties of succinic acid is analyzed using the thermodynamic solvation approach. It is shown that the main contribution to the shift of the acid–base equilibria of succinic acid in aqueous ethanol and aqueous dimethylsulfoxide comes from the weakening of the solvation of its deprotonated forms.

Facile Chemoselective synthesis of 2‐(2‐(Methoxycarbonyl)‐3‐oxo‐2,3‐dihydrobenzofuran‐2‐yl)benzoic acids and 3H,3’H‐Spiro[benzofuran‐2,1′‐isobenzofuran]‐3,3′‐dione derivatives

Oxidation of some derivatives of 4b,9b–dihydroxyindeno[1,2‐b]benzofuran‐10‐one have been investigated in detail using lead(IV) acetate in acetic acid under reflux conditions and periodic acid in aqueous ethanol at room temperature. We realized that during the first 5–15 minutes of the oxidation reactions in lead(IV) acetate/acetic acid system, 3H,3’H‐spiro[benzofuran‐2,1′‐isobenzofuran]‐3,3′‐dione derivatives have been synthesized chemo selectively, while, if the reaction mixtures stirred for additional 3 hours, the main products would be 2‐(2‐(Methoxycarbonyl)‐3‐oxo‐2,3‐dihydrobenzofuran‐2‐yl)benzoic acids. Moreover, room temperature oxidation of 4b,9b–dihydroxyindeno[1,2‐b]benzofuran‐10‐ones by periodic acid (H5IO6), leads to the formation of 3H,3’H‐spiro[benzofuran‐2,1′‐isobenzofuran]‐3,3′‐dione derivatives in good to excellent yields.

Novel and highly efficient synthesis of 3-(alkyl/benzylthio)-9b-hydroxy-1H-imidazo[5,1-a]isoindole-1,5(9bH)-dione derivatives

The oxidation of 3a,8a-dihydroxy-2-(alkyl/benzylthio)indeno[1,2-d]imidazol-8(3H)-ones to give the corresponding 3-(alkyl/benzylthio)-9b-hydroxy-1H-imidazo[5,1-a]isoindole-1,5(9bH)-dione derivatives in good to excellent yields at room temperature using two oxidants, periodic acid in aqueous ethanol and lead(IV) acetate in acetic acid, has been reported.

Phenolic compounds extracted by acidic aqueous ethanol from berries and leaves of different berry plants.

Phenolic compounds of berries and leaves of thirteen various plant species were extracted with aqueous ethanol and analyzed with UPLC-DAD-ESI-MS, HPLC-DAD, and NMR. The total content of phenolics was consistently higher in leaves than in berries (25-7856 vs. 28-711mg/100g fresh weight). Sea buckthorn leaves were richest in phenolic compounds (7856mg/100g f.w.) with ellagitannins as the dominant compound class. Sea buckthorn berries contained mostly isorhamnetin glycosides, whereas quercetin glycosides were typically abundant in most samples investigated. Anthocyanins formed the dominating group of phenolics in most dark-colored berries but phenolic acid derivatives were equally abundant in saskatoon and chokeberry berries. Caffeoylquinic acids constituted 80% of the total phenolic content (1664mg/100g f.w.) in bilberry leaves. B-type procyanidins and caffeoylquinic acids were the major phenolic compounds in hawthorn and rowanberry, respectively. Use of leaves of some species with prunasin, tyramine and β-p-arbutin, may be limited in food applications.

ChemInform Abstract: IPSO‐Hydroxylation of Boronic Acid via Ozonolysis: A Metal‐, Ligand‐, and Base‐Free Method.

Here, we have developed a simple, efficient, and metal-, ligand-, and base-free method for the synthesis of functionalized aryl and alicyclic alcohols via ozonolysis of corresponding boronic acids in aqueous ethanol. The procedure is compatible with a variety of functional groups and can be utilized as an alternative method for the synthesis of hydroxy arenes and alicyclic alcohols.Here, we have developed a simple, efficient, and metal-, ligand-, and base-free method for the synthesis of functionalized aryl and alicyclic alcohols via ozonolysis of corresponding boronic acids in aqueous ethanol. The procedure is compatible with a variety of functional groups and can be utilized as an alternative method for the synthesis of hydroxy arenes and alicyclic alcohols.

Three-component synthesis of pyrano[2,3-d]pyrimidinone derivatives catalyzed by Ni2+ supported on hydroxyapatite-core–shell-γ-Fe2O3 nanoparticles in aqueous medium

Pyrano[2,3-d]pyrimidine derivatives were synthesized via one-pot, three-component condensation reaction of aromatic aldehydes, malononitrile, and barbituric acid in aqueous ethanol catalyzed by Ni2+ supported on hydroxyapatite-core–shell-γ-Fe2O3 nanoparticles (γ-Fe2O3@HAp-Ni2+ NPs) as Lewis acid. The nontoxic nature and easy handling of the catalyst, environmentally friendly and facile work-up procedure, short reaction time, low catalyst loading, and high effectiveness to give products in good to excellent yield are advantages of this approach. Also, γ-Fe2O3@HAp-Ni2+ NPs can be easily recovered and reused for at least six runs.

IPSO-Hydroxylation of Boronic Acid via Ozonolysis: A Metal-, Ligand-, and Base-free Method

Here, we have developed a simple, efficient, and metal-, ligand-, and base-free method for the synthesis of functionalized aryl and alicyclic alcohols via ozonolysis of corresponding boronic acids in aqueous ethanol. The procedure is compatible with a variety of functional groups and can be utilized as an alternative method for the synthesis of hydroxy arenes and alicyclic alcohols.Here, we have developed a simple, efficient, and metal-, ligand-, and base-free method for the synthesis of functionalized aryl and alicyclic alcohols via ozonolysis of corresponding boronic acids in aqueous ethanol. The procedure is compatible with a variety of functional groups and can be utilized as an alternative method for the synthesis of hydroxy arenes and alicyclic alcohols.

Dibutylamine (DBA): A highly efficient catalyst for the synthesis of pyrano[2,3-d]pyrimidine derivatives in aqueous media

Annulated pyrano[2,3-d]pyrimidine derivatives were synthesized via one-pot, three-component condensation reactions of various aromatic aldehydes, malononitrile and barbituric acid in aqueous ethanol using dibutylamine (DBA) as catalyst. The potential application of DBA in organic synthesis is increasing rapidly due to its reaction simplicity, minimal reaction time, high yields of the desired products (83–94%) and low cost chemicals. All of the synthesized pyrano[2,3-d]pyrimidine derivatives were characterized by IR, 1H NMR, 13C NMR and mass spectra.

Synthesis of new annulated pyrano[2,3-d]pyrimidine derivatives using organo catalyst (DABCO) in aqueous media

A selective method for the synthesis of annulated pyrano[2,3-d]pyrimidines has been developed. It was shown that base catalysis is more efficient in this reaction, rather than acid catalysis as it is believed that 1,4-diazabicyclo[2.2.2]octane (DABCO) is N-type base catalyst used for the synthesis of pyrano[2,3-d]pyramidine derivatives via one-pot three component condensation reactions of various aromatic aldehydes, active methylene compounds and barbituric acid in aqueous ethanol carried at normal temperature. The potential application of DABCO in organic synthesis increasing rapidly because of its reaction simplicity, less pollution, and minimum reaction time, high yields of the biological active products, uses less toxic solvents and low cost chemicals.

Physico-chemical properties and components interaction in the solutions of para-substituted benzoic acids in aqueous ethanol

The intermolecular interaction and the structural fitting has been studied in the case of solutions of 4-aminobenzoic and 4-hydroxybenzoic acids in the ethanol-water mixture (70: 30 by volume) by analysis of the density, viscosity, and refractice index data at 303.15 K. Viscometry data has been fitted to the Jones-Dole equation, and the respective parameters have been determined. It has been demonstrated that the introduction of benzoic acids leads to structuring of the aqueous ethanol mixed solvent. Concentration dependences of viscosity and density have revealed the strong interactions between molecules of the solvent and the solute, enhancing with increasing concentration of the acid.

Potassium sodium tartrate as a versatile and efficient catalyst for the one-pot synthesis of pyran annulated heterocyclic compounds in aqueous media

Potassium sodium tartrate (KNaC4H4O6·4H2O) was applied as an efficient catalyst for the one-pot, three-component condensation reactions consisting of aromatic aldehydes, malononitrile, and 4-hydroxycoumarin/dimedone/α-naphthol/thiobarbituric acid in aqueous ethanol. Use of nontoxic reaction components, short reaction times, environmental, easy work-up, and high yields are some important advantages of this method.